Rice (<em>Oryza sativa</em> L.) blast resistance genes bioinformatic analysis

Abstract

Purpose. To investigate rice blast resistance genes polymorphism by using bioinformatic methods. Methods. Global and local nucleotide alignment, phylogenetic analysis, HyPhy test. Results. For Pib gene, numerous single nucleotide substitutions and deletions of 1–3 bp were established. The phylo­geny of this gene has been studied and homologues have been found both in various rice species and in other cereals. These sequences can encode proteins that «recognize» the phytopathogens effectors, and can also be associated with resistance to phytopathogens. The Pi4 gene is characterized by single nucleotide substitutions, insertions and deletions; the number of non-synonymous substitutions exceeds the number of sy­nonymous ones. The Pi54 gene variability is significantly lower than that of the Pi4 and Pib genes. The predominant types of polymorphism were single nucleotide substitutions and small-sized indels. It was found that non-synonymous substitutions in Pi54, Pi4 and Pib genes were in close proximity, sometimes forming clusters, while some coding regions were either superconservative or contained predominantly synonymous substitutions. On philodendrograms, cultivated rice samples were clustered with samples of ancestral wild-growing species. Conclusions. Evolution of the rice blast resistance genes Pi4, Pib and Pi54 is characterized by diversification selection. Considering that tense coevolution and significant rate of adaptation and creation of new pathogen races are typical for a plant and a parasite, these genes are subjected to intensive selection aimed at increasing diversity for obtaining the resistance to new races of the pathogen.

Keywords

• Genes Pib, Pi54, Pi4
• sequence alignment
• phylogenetic analysis
• evolution
• single nucleotide polymorphism
• indels